What happens when there's no wind and wind turbines stop turning? What provides the back up power for this clean energy source on calm, windless days?

ADVERTISEMENT

While wind may be the fastest growing renewable energy source in the US, in order for us to rely on wind power, there needs to be some backup technology to fill in when wind does not blow.

According to Penn State researchers, theoretically, hydropower can step in to provide energy as it can come on line quickly and is also carbon neutral. However, there are large policy and regulation-based barriers that are preventing this from happening.

Researchers looked at the Kerr Dam in North Carolina which powers an electric grid spanning from Pennsylvania through Virginia on the East Coast, west to Indiana and also includes the Chicago area. In addition, the Kerr Dam also supplies other local outlets.

When it comes to power, hydroelectric dams cannot simply release or hold back water to meet demand. Instead, plants operate using guide curves that consider not only electric production, but also drinking water needs, irrigation, fish and wildlife requirements, recreation and minimum levels for droughts. These guide curves are created by the government agencies. In the case of Kerr, the U.S. Army Corps of Engineers is the regulating official, but in other places it could be the U.S. Bureau of Reclamation, the Tennessee Valley Authority, the Colorado River Authority or other entities. These authorities make decisions based on the guide curves that are predicted for one-week weather forecasts.

The researchers determined that the Kerr Dam could accommodate the unexpected variations in wind energy, but only if those operating the dam were allowed to meet the guide curve requirements over a two-week rather than one-week period of time.

"Changing guide curves is complex, time-consuming and may even require an act of Congress," said Seth Blumsack, assistant professor of energy policy at Penn State.

The researchers found that changing the pricing of electricity so that backing up wind is more lucrative than the spot market would not make these multipurpose hydro facilities more prone to supply backup to wind power.

"Operational conflicts may be significantly reduced if the time length of the guide curve schedule was altered, yet such regulatory changes prove quite challenging given the institutional barriers surrounding water rights in the U.S.," said the researchers, who also include Patrick M. Reed, professor of civil engineering, Cornell University.